/Engine/Source/Runtime/GeometryCore/Public/Spatial/OccupancyGrid3.h
Given a point in space, return a computed index into the occupancy grid. If the point is outside of the mesh's bounding box, the given index will be outside the range of the occupancy grid. To check for validity, test against the occupancy grid's extents as returned by GetOccupancy.
[FVector3i](API\Runtime\GeometryCore\FVector3i) GetCellIndexFromPoint ( const FVector & InPoint ) const